1. Field of the Invention
The present invention relates to a method of preparing hydrogen using an amino acid, and more particularly, to a method of preparing hydrogen using an amino acid by which a heating value of hydrogen is reduced when being generated and a hydrogen generation rate is improved.
2. Description of the Related Art
Hydrogen gas, which is a future-oriented environmental-friendly form of providing energy, reacts with oxygen to produce energy and water as a byproduct. Therefore, hydrogen gas can solve a variety of environmental problems that are caused by use of fossil fuels, which are at present our main energy sources. In addition, hydrogen gas can be variously used in fuel cells, hydrogen engines, gas turbines, and the like, and thus much research into the preparation of hydrogen gas as an alternative energy source of fossil fuels has been actively conducted.
A technique for stably and effectively storing and supplying hydrogen is one of the most important techniques required, in terms of using hydrogen gas in a variety of commercial application fields. Recently, sodium borohydride has drawn much attention as a material which can be used to store and generate hydrogen. When a transition metal or a salt thereof is added to an aqueous sodium borohydride solution, borohydride is hydrolyzed, and thus hydrogen gas is generated (Kaufam, C. M. and Sen, B., J. Chem. Soc. Dalton Trans. 1985, 307-313).
U.S. Pat. No. 6,534,033 discloses a hydrogen generation system comprising a stabilized metal borohydride solution and a transition metal catalyst. Herein, not only does the metal borohydride solution function as a hydrogen storage source, but also functions as a catalyst system which releases hydrogen with the transition metal catalyst. Among transition metal catalysts, ruthenium, rhodium, and platinum catalyst have high activity for hydrogen generation at room temperature, however it is too expensive for the catalysts to be disposably used in various application fields.
According to Kojima, Y. et al., Int. J. Hydrogen Energy, 2002, 27, 1029-1034 that has recently been published, it was reported by Toyota Central R&D Laboratories, Inc. that a catalyst containing platinum and LiCoO2 had high catalyst activity in hydrogen generation. However, such a hydrogen generation system still uses precious metals such as platinum, and incurs high manufacturing costs, thereby making it difficult to implement. In terms of practical use, there is a need for a catalyst which has excellent efficiency of hydrogen generation and is also inexpensive.
US2005/0158596 A1 that has recently been published discloses a method of generating hydrogen in an aqueous metal borohydride solution using an organic pigment as a catalyst. In this case, the activity of the organic pigment catalyst is relatively largely affected by pH, and it has also difficulty in fixation of the catalyst. Thus, application of the method in various fields is not easy.
As a method of generating hydrogen, a metal borohydride is hydrolyzed using a metal catalyst, an organic acid, or an inorganic acid (for example, acetic acid, sulfuric acid, and the like), generating a large amount of heat. If a large amount of heat generated is naturally cooled down, the cooling speed is so slow that there are large limitations on adjusting a hydrogen generation amount. Thus, there is a need for installing a cooling system such as a heat exchanger, and the like in a hydrogen generating apparatus. Accordingly, the total size of the hydrogen generating apparatus is required to be increased, and thus a large amount of heat generated is a big drawback in making the hydrogen generating apparatus small in size.
To address these problems, for small-sized hydrogen generating apparatuses, there is an urgent need to develop a method of generating a desired amount of hydrogen, which reduces manufacturing costs and lowers a heating value of hydrogen.